Of the 175 pages released in response to a Courant Freedom of Information request, 64 were completely redacted and most of the other 111 pages were heavily redacted. The Courant submitted the request in January after state police released a report on the Dec. 14, 2012, shooting that left 20 first-graders and six women dead at the Newtown school.

The names of all witnesses interviewed by federal agents have been removed and there are no references to attempts by federal authorities in Washington, D.C., to recover information from a computer disk that shooter Adam Lanza destroyed.

Although the state police Western District Major Crime Squad was the lead group investigating the massacre, federal agents from the New Haven office were heavily involved.

Agents assisted in clearing the school, identifying the victims, canvassing the neighborhood where Lanza lived and interviewing relatives of his mother, Nancy Lanza, in New Hampshire. Nancy Lanza was shot to death in her bed by her son.

Federal agents in New Jersey interviewed Ryan Lanza, the shooter’s older brother, who lived in Hoboken at the time. Authorities initially thought that Ryan Lanza was the shooter because Adam Lanza had an old identification card of his brother’s on him.

The just-released FBI records include an interview, conducted the same day of the shootings, with a man who appears to be Ryan Lanza.

The interviewee told agents that Adam was “computer savvy” had worked briefly at a computer repair shop and that Nancy Lanza owned at least four guns — including the AR-15 used in the massacre — and a .45 caliber pistol.

The interviewee said all the guns were legally bought by Nancy Lanza, but “that Adam actually owned the AR-15, and that all the weapons were kept in a gun safe in Adam’s bedroom closet.” The person said that Adam Lanza had taken an NRA safety certification course that allowed him to fire the .45 caliber pistol at a Danbury shooting range, and that to his knowledge Adam Lanza was able to buy all his ammunition legally.

The person told agents that Adam Lanza had never been violent or used drugs or alcohol. The last line of the interview states the man “could provide no explanation or motive for Adam’s actions.”